The majority of books held by the Bodleian Libraries, in both physical and electronic formats, can be searched via SOLO.
Subject searches to use in SOLO, the Oxford catalogue, include
Maori (New Zealand people) -- Legal status, laws, etc --Maori (New Zealand people) -- Land tenure -- Maori (New Zealand people) -- Claims
Holders of an Oxford SSO wishing for introductory overview or practitioner level explanation of the current law in NZ are advised to start with
Open Access Resources available to anyone with access to the internet
Tikanga Maori : living by Maori values by 
Lords of the Land : indigenous property rights and the jurisprudence of empire by 
The Treaty of Waitangi Companion by 
The Treaty of Waitangi in New Zealand's law and constitution by 
Waitangi revisited : perspectives on the Treaty of Waitangi by Lords of the Land : indigenous property rights and the jurisprudence of empire by The Bodleian Law Library shelves its current collection of comparative law books on Level 2, the level at which you enter the library.
The shelf mark Cw Gen is used when the only jurisdictions compared are (or were) members of The Commonwealth
To find books which might include Māori commentary and analysis try these subject searches in SOLO
Indigenous peoples (International law)
Indigenous peoples -- Legal status, laws, etc
Aboriginal Customary Law: a Source of Common Law Title to Land by The shelf mark General is used when the comparison is wider
Indigenous peoples and the law : comparative and critical perspectives by 
Traditional knowledge, traditional cultural expressions, and intellectual property law in the Asia-Pacific region by The Law Bod shelves its collection of public international law books on Level 3, one floor above the entrance level to the library.
To find books which might include Māori commentary and analysis try these subject searches in SOLO
Indigenous peoples (International law)
Indigenous peoples -- Legal status, laws, etc
Reparations for indigenous peoples : international and comparative perspectives by The New Zealand Geographic Board Ngā Pou Taunaha o Aotearoa has the task of assigning official names to places and significant features in New Zealand and in the Ross Sea region of Antarctica.
If the Bodleian Libraries don't have the book you are looking for, we may be able to source it through Oxford's inter-library request service.